In the conventional rapid charging circuits for rechargeable batteries (to be called hereinafter "batteries"), temperature-sensing or -.DELTA.V (minus delta V) methods have been used. However, the known rapid charging circuits using these methods can rapidly charge only one battery at a time. Further, U.S. Pat. No. 4,571,533 (dated Feb. 18, 1986) discloses an automatic charging apparatus for charging a battery in a rate proportionate to the voltage level of the battery. This charging apparatus is provided with a monitoring device for generating light signals to indicate the voltage level the battery. However, this circuit also has the disadvantage that, if a plurality of batteries are to be charged continuously and rapidly by means of this circuit, the individual battery has to be replaced each time the charging of a battery is completed. Meanwhile, if a plurality of batteries are to be simultaneously charged, then the power supply capacity has to be increased by as many times as the number of the simultaneously charged batteries, and also, a charge control circuit comes to be needed which causes an increasing of the manufacturing cost of the charging circuit.